Metal forming tool



Dec. 14, 1937. F. J. MINKEL, 2,102,572

METAL FORMING TOOL Filed Feb. 26, 1955 2 Sheet-Sheeb l aka/ 7 attorney -De.14,137. v F. J. MINKEL 2,102,572

METAL FORMING TOOL Filed Feb. 26, 19:55 2 She ets-Sheet 2 Zinnentor Clttorneg Patented Dec. 14, 1937 paris sreres METAL FORMING TOOL Frank J; Minkel, Buffalo, N. Y., assignor to Fedders Manufacturing N. Y

Company, Inc, Buffalo,

2 Application February 26, 1935, Serial No. 8,325

3 Claims.

This invention relates to improvements, in metal punching and forming tools.

It is one object of the invention to provide a die mechanism of simple and inexpensive con- 5 struction for providing formations or holes of eiliptical shape in sheet metal structures. Other objects and features of the invention are set forth in the specification and drawings, wherein:

Fig. l is a top View of the die assembly; Fig. 2 is a bottom view of the punch assembly; Fig. 3 is a vertical cross section through the center of the assembled mechanism;

Fig. i is a fragmentary vertical cross section through a punch and the associated die therefor; Fig. 5 is a top view of a radiator tank head provided with elliptical formations;

Fig. 6 is a section on'the line 6-6 of Fig. 5. The mechanism herein shown may be utilized in a power press, and it includes a punch holder 5i! and die shoe M, which are secured to the ram and bed plate 52 and i3 respectively of the press. Guide pins i i are secured to the shoe l l andthey are slidably received in the holder lll-tomaintain alignment of the members. V a The article to be formed inthis mechanism is shown in Fig. 5 as a radiator tank headI-Lwhich is supplied with elliptical 'holes l5 and lit-the latter hole having a peripheral. flange ll adapted to receive a cylindrical pipe 18,. and thus its angle to the horizontal is such as to project a true circle equal to the outside diameter of the pipe- The die assembly consists of a blockiQ secured to the shoe ii and formed with an angular suppcrting face 25 having the same relation tothe horizontal as the flange ll, voxymathematically expressed, the angle corresponds to the secantwhich is equal to the ratio of the major and minor axes of the elliptical formation. A gage member is secured to the shoe at the front of the block 0 and it contains a depression having a wall 23 which serves to support the edge of the head 1-1 when it is placed on the face 2|. The rear surface of the block is provided with a vertical shoulder or step 24, while its central portion is formed with a large vertical bored hole 25 whose diameter is equal to the minor axis of the outside of the flange ll, and four vertical holes 26 disposed in spaced relation thereto.

The bored hole 25 receives a punch 2'! having 50 a cylindrical shank 28, which fits therein, and a cylindrical shouldered punch portion 29. The shank is secured to the shoe i I while the portion its is formed with an angular face 3i co-planar with the block face 2!. The face 3! is addi- 55 tionally formed with a concave depression 32,

the purpose of which will be hereinafter set forth.

Cylindrical dies 33 (Fig. 4) are'pressed into the holes 26' and their upper surfaces are likewise ground to match the block face 2!. Each die is formed with a coaxial die hole 34 which is enlarged at its bottom extremity to coincide with holes 36 in the block E9, the latter holes serving to receive the scrap punchings from the dies.

A punch block 38 is secured to the punch holder iii and it is formed with a shouldered vertical hole 39 for receiving the flanged shank M of a die 42.

The free extremity of this die is. cut to the angle of the face 2% and it is of tubular form, having an inner circular cutting edge 63 serving as a die f or receiving the underlying punch portion 29 of the punch 2'5. The end face of the tubular portion is bevelled from the edge -3, as indicated by the numeral it, at an angle constant with the plane of the face 2!. The clearance between the die 52 and the underlying bored hole 25 in the block W is slightly greater than the thickness of the metal of the head or blank H.

A stripper 56 is disposed within the tubular portion of the die if and it is secured to the shank M thereof by a screw ll. The extremity of this member is shouldered and formed with an angular face it having a convex form cor responding to thefconcave formation 32. of the punch 2i.

The block 38 is formed with oles $9, each of which receives the shank 5i of a punch 52. The ends of these punches are provided with reduced cylindrical portions each adapted to be received in the hole as of a die 33.

A pressure pad 55 is formed with a large vertical bore 563 and four small vertical holes 50 which slidably receive the die 62 and shanks 5| of the punches E2, respectively. Springs 5'l'are mounted in aligned counterbores 58, 59 in the block 33 and pad 55, respectively, and they tend to separate the members. However, this movement is limited by screws 6i secured to the pad 55 and having heads 52 slidably engaging in suitable counterbores in the block 38.

The surface of the pressure pad 55 is formed with an angular face 6t, parallel to the face 2| of the die block i9, and also with a heel portion 63 adapted to engage slidably the step 24 of the same block. To reinforce the end portions 53 of the punches 52 against lateral movement, bushings 6d are pressed into the holes 50 adjacent the face 62, and they slidably receive the portions 53.

In operation, the sheet metal head blank H is positioned on the face 2i with its lower edge en gaging the gage wall 23. The press is then operated to move the punch holder assembly toward the die assembly, whereupon the pressure pad 55 first resiliently clamps the blank between its surface and the block face 2|, which action is immediately succeeded by the simultaneous blanking of the four small holes H: by the action of the punches 52 and dies 33, and the blanking of the large central hole IS; the latter action being obtained through the cooperation of the depending die or cutting edge 43 of the die 42 with the punch portion 29 of the punch 21. Upon further movement of the press, the bevelled face 44 of the die 42 engages the metal at the periphery of the hole previously formed and draws this metal downward about the edge of the bored hole 25 to form a peripheral flange.

At the bottom of the punch stroke, the concave and convex surfaces of the punch 21 and stripper 46 form the blanked metal portion of the central hole into a concave shape, thus reducing the diametral size thereof, so that upon the upward stroke of the press this piece of metal will not cling to the die 42, but rather will remain on the angular face of the punch 21, where it may easily be removed. During the described operations, the heel 63 and step 24 cooperate to resist the horizontal loads, thus protecting the die structure from shearing stresses.

Special attention is directed to the fact that although the holes and formations obtained by the described operation are elliptical in the sheet H, the punches, dies and guide formations therefor are all of true cylindrical shape. This permits the machining and grinding of these elements in the lathe or boring mill, and it eliminates the arduous task of filing and fitting elliptical punches and dies, as previously utilized.

It will be obvious that the principle herein disclose-d may be varied in numerous manners, and may be used in many fields of metal forming Without departing from the inventive concept as set forth in the following claims.

I claim:

1. In a die mechanism for providing elliptical flanged holes in sheet metal blanks, a tool comprising a tubular punch having an outside diameter substantially equal to the minor axis of the hole to be formed and having an inside cutting edge and an outside forming edge for forming the flange in the blank, a second tool comprising a die block having a cylindrical forming die opening for cooperation with the forming edge of the tubular punch, and a cylindrical punch mounted concentrically within the die block opening and adapted to cooperate with the cutting edge of the tubular punch, means for mounting said tools for relative movement toward each other with their punch and die formations disposed in coaxial alignment, one of said tools being provided with supporting means for the blank inclined at an angle to the axis of the formations, said punch and die formations of the tools being formed with angular extremities substantially parallel to the supporting means.

2. In a die mechanism for providing elliptical flanged holes in sheet metal blanks, a tool comprising a tubular punch having an outside diameter substantially equal to the minor axis of the hole to be formed and having an inside cutting edge and an outside forming edge forforming the flange in the blank, a second tool comprising a die block having a cylindrical forming die opening for cooperation with the forming edge of the tubular punch, and a cylindrical punch mounted concentrically Within the die block opening and adapted tocooperate with the cutting edge of the tubular punch, means for mounting said tools for relative movement toward each other with the punch and die formations disposed in coaxial alignment, said die block having a supporting surface for the blank inclined at an angle to the axis of the formations, said punches being also formed with angular faces parallel to the supporting surface of the die block.

3. In a die mechanism for providing elliptical flanged holes in sheet metal blanks, a tool comprising a tubular punch having an outside diameter substantially equal to the minor axis of the hole to be formed and having its terminal portion formed at an angle to its axis and formed with an inside cutting edge and an outside forming edge for forming the flange in the blank, a cylindrical stripper mounted concentrically within the punch and having an angular terminal portion parallel to the terminal of the punch and having a convex shape, a second tool comprising a die block having a cylindrical forming die openingfor cooperation with the forming edge of said punch and a cylindrical punch mounted concentrically within the die block opening and adapted to cooperate with the cutting edge of the tubular punch, means for mounting said tools for relative movement toward each other with their cylindrical formations in axial alignment, said block being formed with an angular face parallel to the terminal portion of the tubular punch, and said cylindrical punch having a similarly inclined terminal portion formed with a FRANK J. IVIINKEL. 

